In regard to an internal combustion engine, supercharged lean burn, a large amount of EGR, and homogeneous-charge self-ignition combustion have been actively studied in recent years for CO2 reduction and emission reduction. According to these studies, in order to maximize effects of the CO2 reduction and the emission reduction, it is necessary to realize a stable combustion state near a combustion limit. Also, while petroleum fuel is being depleted, robustness in stable combustion with various fuels such as biofuel is required. A most important factor for realizing the stable combustion is to reduce an ignition fluctuation of a fuel-air mixture, and to realize homogeneous and stable combustion without any unevenness. This requires easier vaporization by fine fuel spray and uniform atomized particle sizes.
Further, a fuel supply of the internal combustion engine adopts a cylinder injection system in which fuel is injected directly to a combustion chamber for the purpose of improving transient response, improving volume efficiency by evaporation latent heat, and carrying out greatly retarded combustion for catalyst activation at low temperatures. However, the adoption of the cylinder injection system may cause oil dilution caused when spray fuel hits a wall of the combustion chamber as the spray fuel is in a form of liquid droplets, PM (Particulate Matter), and generation of smoke.
In order to take measures against these phenomena, a swirl flow may be given to fuel injected from a fuel injection valve. As the fuel injection valve configured to give a swirl flow to fuel, Patent Document 1 and Patent Document 2 have been known, for example. Particularly, Patent Document 2 describes a fuel injection valve configured such that a swirling component is given to fuel so that fine air bubbles are taken in injected fuel, thereby achieving atomization of the injected fuel by bursting the fine air bubbles.